Immediately ahead of it was the Montrebeau Wood, which the Germans had been fortifying since they recovered it from the 35th; beyond that the deep broad Exermont ravine, guarded in the center by the Montrefagne, or Hill 240, with its crest crowned by woods which covered its slopes almost to the edge of the ravine. This was only the highest of the series of hills which extended west to east from the Aire valley across the sector of the 32nd. When the first series was taken, other hills still higher commanded the valleys and reverse slopes beyond, in a witchery of irregularities which had their culmination in a final congeries of wooded hills in front of the Kriemhilde Stellung of the whale-back, some six miles beyond the 1st's line of departure. Every open space was covered by interlocking machine-gun nests supported by artillery concentrations. Ravines were corridors for the sweep of fire; or if they gave cover their ends were sealed by fire. With its left moving along the eastern wall of the Aire, its flank naked to the fire from the western wall, the 1st was to drive a human wedge over these hills in order to gain one of the two sides of the trough, whose interlocking and plunging fire, as we have seen, had stayed the First Corps in the trough and in the Forest. Of course, the 1st would "go through" at the start. Its own record and standards compelled it to go through. It would make the wedge. What would be the result after the wedge was made? Unless the point of the wedge were protected by a spreading movement at its base, it would be crushed by pressure from both sides. Here the part of the 32nd became vital in gaining the hills on its front, which, remaining in the enemy's hands, would threaten the right of the 1st with a fire interlocking with that from the western wall of the Aire. In the valley of the Aire, of course, the Pennsylvanians of the 28th were to try to advance under cover of the 1st's thrust. If they were checked, and the 32nd were also checked, the Germans would not be slow to see or to improve their opportunity to force a repetition of the bloody result of Pickett's charge and of the assault at Cold Harbor.